Catalytic reactors are known for promoting chemical reactions. Heterogeneous catalytic reactors are referred to herein.
Jet impingement of a fluid onto a solid surface is known to increase the heat transfer coefficient near the surface for applications such as cooling turbine veins and electronic components. U.S. Pat. No. 5,029,638, the entire disclosure of which is incorporated herein by reference in its entirety, teaches jet impingement and suitable configurations to assist heat transfer in a compact heat exchanger.
U.S. Pat. Nos. 5,350,566, 5,651,946 and 4,719,090, referred to collectively herein as the three patents, and each of which is incorporated herein by reference in its entirety, each teach permeable, engineered structures which may be used for catalysis and which provide mixing of process fluid by enhancing turbulence throughout a reactor. The three patents each utilize corrugated sheets with the corrugations inclined at an oblique angle to the general direction of fluid flow from respective reactor inlets to their outlets. The corrugated sheets are perforated or have spaces between them or both. The obliquely inclined corrugations induce a lateral component to the fluid velocity. The perforations or spaces between the corrugated sheets provide lateral return paths for the fluid to maintain zero net lateral flow through the reactors. Lateral flows are induced at smaller scale distances while at larger scale distances net lateral flow is balanced. Each of the three patents teaches promoting mixing. The designs accordingly do not preserve lateral momentum, but combine fluids with opposite lateral component velocities, effecting mutual annihilation of their respective lateral momentums. Such designs, while effective for mixing, are less effective for the destruction of a boundary layer at a reactor wall or for increasing the heat transfer coefficient near the reactor wall than the projection of jets to impinge reactor walls at a low angle of incidence.
Further, the three patents utilize parallel stacks of corrugated sheets at alternating inclinations. Because the sheets are in flat, parallel planes, the channels are chordal to the reactor cross section. This results in some channels being normal to the reactor wall near some parts of the reactor wall and being parallel to the reactor wall near other parts of the reactor wall, making them less effective and less consistent in increasing heat transfer at all parts of the reactor wall than radially arrayed channels.
European Patent No. EP0025308 A1, the entire disclosure of which is incorporated herein by reference in its entirety, teaches an apparatus to cause fluid to flow alternatingly through a reactor core structure and through a space between the core structure and the vessel wall. This patent does not teach the destruction of the boundary layer at the reactor wall by jet impingement. All embodiments teach extensive fluid flow parallel to the reactor wall through an empty space between the reactor wall and the packing. The patent also teaches two alternative types of structure. One uses a perforated structure and the other uses an unperforated or solid structure. Where perforated structures are used, fluid flow is largely axial with turbulence and mixing in transverse directions and flow near the reactor wall is parallel to that wall in the axial direction. Such flow is ineffective for destroying a fluid boundary layer at a reactor wall relative to jet impingement. Where solid sheets are used, the open or effective cross sectional area of the reactor is compromised because the flow passages within the central structure communicate with each other only via the empty space between the core structure and the reactor wall. This constraint amplifies pressure drops relative to a suitably perforated structure or one in which crisscrossing channels generally communicate with each other.
Use of truncated cones in EP0025308 A1 is anticipated exclusively for annular reactor cross sections. Such truncated cones are either perforated or placed in alternating zones in series to cause alternating centrifugal and centripetal flow along the reactor length. Fluid flow paths extensively parallel to the reactor wall are described in detail for all embodiments. The use of an empty space between the core structure and the reactor wall promotes axial flow along the surface of the reactor wall instead of extensive, uniformly and finely distributed jet impingement of the reactor wall.
U.S. Pat. No. 4,985,230, the disclosure of which is incorporated herein by reference in its entirety, teaches the transmission of heat from a first wall to a second wall via fluid passing through channels that alternately project the fluid toward a first and second wall. The walls are parallel to and uniformly spaced from each other. The channels support a catalyst for performing heterogeneous catalysis of the fluid. One wall is a reactor wall and the other wall is an internal wall within the reactor. This art may be beneficial for the particular application of annular or bayonet reactors such as are used in steam reforming, but can not be applied to a cylindrical or other solid shaped reactor. The radially aligned channels in U.S. Pat. No. 4,985,230 are bounded in the axial directions and must be fed by laterally flowing fluid. Because the channels converge at the reactor axis they necessarily have reduced width or cross sectional area nearer the reactor axis than near the reactor wall. If such a packing were used throughout a cylindrical reactor the reduced cross sectional area of the converging walls near the reactor axis would restrict flow of fluid through channels, making heat transfer ineffective. Extension of the channels to the reactor axis would also substantially increase undesirable pressure drop through the reactor.